Media handling devices such as finishing devices and feeders are known. In current finishing devices and feeders, various methods are used to identify and control the media elevator's current position.
Current methods involve three (3) photoelectric optical or “light” sensors. A first “comb” sensor and a second “limit” sensor are mounted on the elevator itself. A third “full” sensor is mounted near the elevator's bottom or “paper full” position.
The comb and limit elevator sensors, in turn, are arranged to detect two patterns of holes or notches that are fabricated in a metal bracket that is fixed near the elevator travel path. While the bracket solid areas prevent light transmission, the opposing bracket hole or notch areas allow light transmission. Hence, the comb and limit sensors are readily able to detect these bracket hole or notch patterns.
The comb sensor detects the elevator's movement by sensing a “comb”-like pattern of intermittent protruding bracket fingers. Thus, as the elevator travels between the top and bottom positions, the comb sensor traverses the intermittent bracket fingers. As the comb sensor traverses a bracket finger area, the bracket finger prevents light transmission and the comb sensor output turns “off”. Conversely, when the comb sensor traverses a gap between adjacent bracket fingers, the gap area, being free air, allows light transmission and the comb sensor output turns “on”. Hence the comb sensor detects elevator movement by sensing alternating intermittent “on” and “off” light patterns while traversing bracket fingers.
The limit sensor detects the elevator's top-limit and bottom-limit positions by sensing two holes or “notches” fabricated in the bracket top and bottom end regions. The top-limit position is detected by the limit sensor detecting the bracket top notch. The bottom-limit position is detected when the limit sensor detects the bracket bottom notch and the “full” sensor detects an elevator protruding “flag” member that prevents light transmission in the elevator's bottom-limit position.
These present methods further utilize various algorithms to determine elevator position and direction. These methods require the elevator to initialize (home) at some position which is usually at the top or bottom of travel. They measure position in the middle of travel by counting from the home position using stepper motor steps or sensor steps using a linear encoder. Often this process requires the elevator to travel to the bottom (or top) of its range to home, and then the desired intermediate position during printer cycle up. This method takes a long time and can be costly depending on its complexity.
Thus, there is a need for the present invention.